In a field of display, organic light-emitting diode (OLED) display panels have a broad development prospect due to characteristics such as self-illumination, high contrast, low power consumption, a wide viewing angle, fast response, capability of being used in a flexible panel, a wide usage temperature range, simplicity in fabrication, and so on. Due to the above-described characteristics, the organic light-emitting diode (OLED) display panels may be applied on mobile phones, monitors, laptops, digital cameras, instruments and other devices having a display function.